Embodiments disclosed herein relate to ink compositions comprising an amorphous component, a crystalline material, and optionally a colorant, and methods of making and using the same. In particular, embodiments disclosed herein relate to ink compositions comprising an amorphous component exhibiting improved thermal stability and improved distribution in ink preparations.
Ink jet printing processes may employ inks that are solid at room temperature and liquid at elevated temperatures. Such inks may be referred to as solid inks, hot melt inks, phase change inks and the like. Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording medium (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the recording medium, so that migration of ink along the printing medium is prevented and dot quality is improved.
A recently developed phase change ink formulation utilizes a mixture of crystalline and amorphous materials. The crystalline material imparts a hardness and rapid phase change that is beneficial for direct-to-paper (DTP) print architectures. The amorphous material (typically a viscous, tacky material) aids in adhesion of the ink to the substrate and plasticizes the crystalline component to prevent embrittlement and cracking of the printed image. The majority of amorphous materials disclosed thus far have been ester-based materials. These crystalline-amorphous inks display improved robustness over known inks on coated substrates with respect to scratch, fold and fold offset. A commonly employed ester-based amorphous component is a derivative of L-tartaric acid/cyclohexanol/t-butylcyclohexanol (TBCT) which is considered to contribute to the acceptable robust images. However, TBCT suffers from several disadvantages, namely thermal stability during synthesis and variation in product distributions, both of which pose challenges for scale-up synthesis.